From your post, I'm surmising you have not yet obtained/heard a copy of the rerelease? In Owen's notes which are included in the rerelease, she describes some of the process and she is in a far better position than I to reply further.

Simply stated, she and Lewis Merenstein (the album's original producer) went into SONY (RCA's successor) and retrieved the actual tapes laid down in London in the summer of 1972. They used the actual tapes, rather than retreading the album. There seems to have been a problem in the transfer from these actual tapes to the recordings released in the Fall of 1972. As far as further technical matters, I defer.

Sony/BMG ordered the tapes out of the cold storage vault. We remastered the record from the 1/4 inch master mix tapes...not the 2 inch multi-track tapes, which are, to our knowledge, are in London, stored in the RCA/BMG/SONY vaults there. I imagine that there wasn't a need to ship those multitracks back to the US, as the record was "mixed down" in London..

As I stated in my lines notes, the miracle was that, one of the quarter inch mix tapes contained a re-mix of the first single on TRINPFAL, :"If You're Gonna Break Another Heart", which we utilized on the remastered CD.

As far as further technical information goes...I have no idea what exactly was "tweaked" in the remastering of these albums. I was there..but many knobs were turned...!!